1. Field of the Invention
The present invention relates to a method of and an apparatus for generating an incoming ring in a digital cordless telephone, and more particularly to a method for selectively generating an incoming ring from a mobile station, namely, a handset, in response to an incoming call from only a selected one of base stations in which the handset is registered for its operation.
2. Description of the Related Art
Generally, analog cordless telephone systems operate in such a manner that a limited number of handsets are registered in one base station in room environments such as homes or offices. On the other hand, digital cordless telephone systems operate in such a fashion that a plurality of handsets are registered at one base station. In particular, digital cordless telephone systems, such as second generation cordless telephone (CT2) systems, can operate not only in such a fashion that a plurality of handsets are registered at one base station, but also in such a fashion that, as shown in FIG. 1, each handset HS is registered at a plurality of base stations BS1, BS2, BS3, . . . , and BSn, respectively. In such digital cordless telephone systems, when an incoming call is generated, the base station receiving the incoming call polls all handsets registered therein in accordance with a ring generation protocol, which is shown in FIG. 2, so that all the handsets can generate incoming rings. In this case, the base station also sends data about its base station identification (hereinafter, referred to as "BID") upon polling the handsets. Accordingly, each handset checks whether or not the BID received therein is associated with one of the base stations in which it is registered. The handset generates an incoming ring when the BID received therein is associated with one of base stations in which it is registered.
However, the handset always generates incoming rings of the same characteristic irrespective of different base stations in which the handset is registered. As a result, the user of the handset can not recognize the base station which is associated with the generation of the incoming ring even though he can hear the incoming ring output from the handset. For this reason, where the user wants to receive only a call associated with the incoming ring from a desired base station, there is an inconvenience in that the user should directly identify the BID of the base station displayed on the display panel of the handset. It is impossible to identify the base station associated with the generation of the incoming ring without identifying the BID of the base station.